Nitretação a plasma de ligas Ti-Zr-Si-B tratadas termicamente

Abstract

The objective of this work was the surface treatment of plasma nitriding of heat treated Ti-Zr-Si-B alloys. The Ti-Zr-Si-B alloys were produced by the arc melting process, followed by a structural characterization step, carried out with the aid of optical microscopy, scanning electron microscopy, EDS and DRX techniques. Vickers microhardness tests of the Ti-Zr-Si-B alloys were heat treated at 1200ºC for 16 h. After the analysis of the alloys, plasma nitriding was carried out in the alloys with an increase in temperature of 650°C, 700°C and 750°C, maintaining the nitriding time 5h, the pressure (6.90 torr) and the gas constant (80% vol N2 and 20% vol H2) were used in order to determine the best conditions for the formation of the nitride layer. The Vickers microhardness of the nitrided alloys increased with increasing plasma nitriding temperature and formed a layer in all alloys. Among the plasma nitriding conditions of the studied alloys, the Ti-6Zr-6Si-3B (%at.) alloy plasma nitrided at 750°C presented the highest microhardness value of 1984 HV. In all nitriding conditions, the formation of ε-Ti2N and γ-TiN compounds was found in the XRD analysis, confirmed by the golden color of the sample.